Catalytic cracking of hydrocarbons



' PatentedMar. 7, 1944 CATALYTIC CRACKING F HYDROCARBONS Mathias Pier, Heidelberg, and Gerhard Free, Luden-onthe-Rhin e, Germany; vested in the Alien Property Custodian No Drawing.

Application May 6,1941, sci-m No. 4. In Germany May 6, l9

s'clsims. (01.196-49) The present invention relates to the catalytic cracking of hydrocarbons.

We have found that in the cracking of hydrocarbon oils mainly boiling above 2.50 C. by leading them over rigidly arranged catalysts the yield of low-boiling substances, in particular non-knocking motor fuels, can be increased and the nature of the products improved if the starting materials are passed through more than one reaction zone, the material being introduced into the first zone at an elevated pressure not higher than 25 atmospheres and thepressure being reduced between at least two reaction zones by at least atmospheres, for example by means of regulating valves, without substantially reducing the temperature, the last reaction zone containing synthetic magnesium silicate as a cracking catalyst. At least in the last reaction zone the initial materials are to'be completely in a vaporous state.

As initial materials there may be mentioned in particular hydrocarbon rich in hydrogen and capable of being vaporized under the reaction conditions obtained for example from petroleum,

destructive hydrogenation products and the like, for example heavy oils stituents of middle oil character. The hydrocarbon mixtures obtained by the reduction of carbon monoxide are especially suitable initial materials.

Hydrocarbons rich in hydrogen may also be worked up in admixture with hydrocarbons lower in hydrogen, in particular aromatic hydrocarbons.

From the initial materials rich in hydrogen there are thus obtained in good yields benzines which are non-knocking and contain compara-' tively small amounts of unsaturated hydrocarbons because during the treatment there takes place an isomerization of the hydrocarbons which causes a high octane number and high lead susceptibility.

The process according to the present invention is carried out in the first reaction zone at a pressure of from 5 to atmospheres, especially at a pressure of from 5 to 15 atmospheres, and then, without separation of the benzine formed, in the seciind zone at a lower pressure, preferably at a pressure lower by from 5 to 25 atmospheres than that first used. It is advantageous to work in the last zone under atmospheric pressure. Temperatures of from 350 to 700, preferably from 400 to 600 C., are used and the temperatures in the single pressure stages may be approximately the same. However, the process may also be carried out at increasing temperatures; the inwhich may contain concrease may amount to irom 10 to preferably from 15 to 50 C.

As has been mentioned above, the last reaction zone, 1. e., the one operated at alower pressure, contains a synthetic magnesium silicate as a cracking catalyst. The said silicate may be prepared, for example, by uniting an acidified water glass solution with a magnesium salt solution, for example a solution of magnesium chloride, washing the resulting Jelly or hydrogel and drying and heating'it. The magnesium may be dis solved out in part during the manufacture of the catalyst or from the finished catalyst, for example by means of an appropriate acid. The reaction zone operated at higher pressure may be kept free from catalysts and be empty'or, if desired, provided only with adsorbing agents, such as for example bleaching earth or alumina or active carbon or inert filler substances, as for instance, pumice stone, clay sherds or Raschig rings, or there may be used a less strongly active catalyst, as for example a catalyst which has been used for a long time.- i 7 v The catalysts are usually used for only a short time, as for example from 20 minutes to 2 hours, I

and then regenerated. for example with gases containing oxygen, preferably thosehaving gradually increasing oxygen content. at increasing temperature. and then used again, if desired in admixture with fresh catalyst.

' The following examples will further illustrate the nature of this invention but the invention is not restricted to these examples.

sample 1 Two reaction chambersconnected in seriesand arranged one above the other are filled with catalysts in the form oi pieces. he catalyst in the first chamber consisting of bleaching earth and that in the second chamber of magnesium silicate prepared according to the application Ser. No. 222,144, filed July 30, 1938. The reaction chambets are heated to 460' C. A regulating valve is provided in the connecting pipe. A middle oil obtained from German petroleum and boiling between 250 and 390i C. is led in a preheated condition into the upper part of the first chamber, the regulating valve being closed. By reason of the vaporization of the oil. an increased pressure is set up'in the first chamber. The realism valve is thenv opened in such a manner that a pressure of 20 atmospheres is maintained in the first chamber. The product released from presicate OHM- 8st.

liter of oil per By working Example 2 An asphalt base petroleum distillate with an initial boiling point of 250 C. of which 40 per cent boil up to 350 C. is passed at 480 C. through a reaction chamber which is fllled with lumps of burnt clay; this chamber may be closed by a valve and a pressure of 10 atmospheres is produced init by the vaporization of the oil which pressure is constantly maintained by the valve. The oil vapors are continuously released to atmospheric pressure into a second reaction chamber which is filled with magnesium silicate synthetically produced, whereby the throughput is 1 liter of oil per 1 liter of catalyst. A reaction product is obtained with 28 per cent of benzine.

What we claim is:

10 knocking motor fuel, which comprises passing 1. A process for the production of a non-knocking motor fuel, which comprises passing a hydrocarbon fluid mainly boiling above 250 C. and capable of being vaporized under the reaction conditions, at a cracking temperature through more than one-reaction zone, the initial material being introduced at a pressure not higher than 25 atmospheres and the pressure between at least two reaction zones being reduced by at least 5 atmospheres without substantially reducing the temperature, the last reaction zone containing a synthetic magnesium silicate as a cracking catalyst and thereby surpassing any previous reaction zone as to the catalytic cracking effect.

2. The process as claimed in claim 1 in which the reaction zone with the highest pressure is provided with a less strongly active cracking catalyst.

3. The process as claimed in claim-1 in which the reaction zone with the highest pressure is provided with an adsorbing agent.

4. The process as claimed in claim 1 in which the reaction zone with the highest pressure is free from catalyst.

5. A. process for the production of a nona fluid mainly boiling above 250 C. and capable of being vaporized under the reaction conditions, at a cracking temperature through two reaction zones in succession, maintaining a superatmospheric pressure of at the most 25 atmospheres in the first reaction zone, reducing the pressure on the hydrocarbon fluid by at least about 5 atmospheres before passing it to the second reaction zone without substantially reducing the temperature, said last mentioned reaction zone containing a synthetic magnesium silicate as a cracking catalyst and thereby surpassing said first reaction zone as to the catalytic cracking eflect.

6. A process for the production of a nonknocking motor fuel, which comprises passing a hydrocarbon fluid mainly boiling above 250 C. and capable of being vaporized under the reaction conditions, at a cracking temperature through two reaction zones in succession, mainhydrocarbon taining a superatmospheric pressure of about 10 atmospheres in the flrst reaction zone which zone is provided with an adsorbing agent, reducing the pressure on the hydrocarbon fluid to about atmospheric pressure before passing it .in the vapor phase to the second reaction zone without substantially reducing the temperature, said last mentioned reaction zone containing a synthetic magnesium silicate as a cracking catalyst.

MATHIAS PIER. GERHARD FREE. 

